Field of the Invention
The present invention relates to a robot apparatus in which a tool device is mounted on a hand device.
Description of the Related Art
Currently, a robot is applied to a manufacturing apparatus in a factory, and parts are transferred and/or assembled with the use of the robot. This type of robot is structured so as to have an electrically-operated robot hand (hand) attached to the head of a robot arm (arm) of a multi-axis and a multi-joint, or of a linearly moving arm.
One robot is needed to perform a plurality of operations for a limited production of a wide variety of products, and as a method therefor, the robot is occasionally made to grip in a hand an electrically-operated tool which can perform the operation that is hard to be performed by the hand, and makes the electrically-operated tool perform the operation. The tool is, for instance, a pincette tool which performs the transfer or the assembly for a small work or a thin work, or an absorbing chuck tool which absorbs and acquires a work.
An electric power can be supplied to and a signal can be a transmitted to the tool, if a contact point of the hand is electrically connected with a contact point of the tool when the hand grips the tool. The tool can be driven by the electric power and the signal which are thus supplied from the hand.
However, there has been a case where the sufficient electric power cannot be supplied and the signal cannot be transmitted because a contact resistance increases and a voltage drop becomes large in the connection portion between the contact point of the hand and the contact point of the tool, due to a contact failure, an aged deterioration and the like.
On the other hand, in order to avoid a stop of the apparatus due to the contact failure and the aged deterioration in the connection portion between the contact points, a method is proposed which detects the contact resistance between the contact points (Japanese Patent Application Laid-Open No. 2007-298288).
In the method disclosed in Japanese Patent Application Laid-Open No. 2007-298288, in order to measure the contact resistance between the contact point on a main body side and the contact point on a load side, a reference resistance is connected in series to the contact point on the main body side; the contact point for measurement is provided on the main body side and the contact point for measurement is provided on the load side, respectively; and the contact point and the contact point for the measurement are short-circuited on the load side. Then, a detecting unit arranged on the main body side detects a potential difference occurring in the reference resistance, and a potential difference occurring in a series circuit of the contact point in the main body side, the contact point in the load side, the contact point for the measurement in the load side and the contact point in the main body side; and grasps the contact resistance based on those detection results.
It is also considered to apply the configuration of Japanese Patent Application Laid-Open No. 2007-298288 to the robot apparatus having the hand and the tool, but the hand and the tool have each a plurality of contact points, and accordingly it has been necessary to increase the contact point for the measurement for each of the contact points, respectively. Then, there is a necessity of increasing the number of the contact points. Accordingly, the hand and the tool have been upsized and also the number of parts have increased, which have consequently caused increase in the cost.